<template>
  <div class="canvas-box" :style="{ height: contentHeight + 'px' }">
    <canvas
      id="id-canvas"
      class="id-canvas"
      :width="contentWidth"
      :height="contentHeight"
    ></canvas>
  </div>
</template>
<script setup lang="ts" name="Identify">
interface IProps {
  identifyCode?: string // 默认注册码
  fontSizeMin?: number // 字体最小值
  fontSizeMax?: number // 字体最大值
  backgroundColorMin?: number // 验证码图片背景色最小值
  backgroundColorMax?: number // 验证码图片背景色最小值
  dotColorMin?: number // 背景干扰点最小值
  dotColorMax?: number // 背景干扰点最小值
  contentWidth?: number // 容器宽度
  contentHeight?: number // 容器高度
}
const props = withDefaults(defineProps<IProps>(), {
  identifyCode: '1234',
  fontSizeMin: 25,
  fontSizeMax: 35,
  backgroundColorMin: 200,
  backgroundColorMax: 220,
  dotColorMin: 60,
  dotColorMax: 120,
  contentWidth: 100,
  contentHeight: 40,
})
// 生成一个随机数
const randomNum = (min: number, max: number) => {
  return Math.floor(Math.random() * (max - min) + min)
}

// 生成一个随机的颜色
const randomColor = (min: number, max: number) => {
  let r = randomNum(min, max)
  let g = randomNum(min, max)
  let b = randomNum(min, max)
  return 'rgb(' + r + ',' + g + ',' + b + ')'
}

const drawPic = () => {
  let canvas = document.getElementById('id-canvas') as HTMLCanvasElement
  let ctx = canvas.getContext('2d') as CanvasRenderingContext2D
  ctx.textBaseline = 'bottom'
  // 绘制背景
  ctx.fillStyle = '#e6ecfd'
  ctx.fillRect(0, 0, props.contentWidth, props.contentHeight)
  // 绘制文字
  for (let i = 0; i < props.identifyCode.length; i++) {
    drawText(ctx, props.identifyCode[i], i)
  }
  drawLine(ctx)
  drawDot(ctx)
}

const drawText = (ctx: CanvasRenderingContext2D, txt: string, i: number) => {
  ctx.fillStyle = randomColor(50, 160) // 随机生成字体颜色
  ctx.font = randomNum(props.fontSizeMin, props.fontSizeMax) + 'px SimHei' // 随机生成字体大小
  let x = (i + 1) * (props.contentWidth / (props.identifyCode.length + 1))
  let y = randomNum(props.fontSizeMax, props.contentHeight - 5)
  const deg = randomNum(-30, 30)
  // 修改坐标原点和旋转角度
  ctx.translate(x, y)
  ctx.rotate((deg * Math.PI) / 180)
  ctx.fillText(txt, 0, 0)
  // 恢复坐标原点和旋转角度
  ctx.rotate((-deg * Math.PI) / 180)
  ctx.translate(-x, -y)
}

const drawLine = (ctx: any) => {
  // 绘制干扰线
  for (let i = 0; i < 4; i++) {
    ctx.strokeStyle = randomColor(100, 200)
    ctx.beginPath()
    ctx.moveTo(
      randomNum(0, props.contentWidth),
      randomNum(0, props.contentHeight),
    )
    ctx.lineTo(
      randomNum(0, props.contentWidth),
      randomNum(0, props.contentHeight),
    )
    ctx.stroke()
  }
}

const drawDot = (ctx: any) => {
  // 绘制干扰点
  for (let i = 0; i < 30; i++) {
    ctx.fillStyle = randomColor(0, 255)
    ctx.beginPath()
    ctx.arc(
      randomNum(0, props.contentWidth),
      randomNum(0, props.contentHeight),
      1,
      0,
      2 * Math.PI,
    )
    ctx.fill()
  }
}

onMounted(() => {
  drawPic()
})

watch(
  () => props.identifyCode,
  (val) => {
    console.log(val)
    drawPic()
  },
)
</script>
<style lang="scss" scoped>
.canvas-box {
  cursor: pointer;
  .id-canvas {
    height: 100%;
  }
}
</style>
